This application articulates a new theoretical framework for understanding processes that govern short-term versus long-term behavior change, and proposes 2 studies based on this theoretical framework that target long-term smoking cessation and weight loss. This conceptualization of the processes of behavior change argues that short-term behavior change is motivated by the expectation that change in behavior will produce desired outcomes (approach motivation). Maintenance of behavior change, however, is motivated by satisfaction with the benefits afforded by current behavior and by the desire to avoid losing those benefits (avoidance motivation). Thus, interventions that raise people's expectations about the benefits of behavior change should increase short-term success, whereas those that raise people's satisfaction with their current behavior should increase behavioral maintenance. Although raising expectations may facilitate short-term success, it may lead to unmet expectations and, thus, undermine motivation for behavioral maintenance. Study 1 tests the effects of intervention strategies that influence outcome expectations. In parallel studies, smokers and overweight individuals will receive treatments that present the benefits of change in "optimistic" or "realistic" terms. It is expected that optimistic outcome expectations will increase short- and long-term rates of smoking cessation, but that realistic expectation conditions will increase long- term weight loss. Study 2 involves parallel studies of smokers and overweight individuals who are randomized to interventions that differ in how people are taught to evaluate their progress. In one condition, their achievements will be evaluated with respect to past outcomes. In the other, achievements will be evaluated in comparison with possible future outcomes. It is expected that both smokers and overweight people will be more satisfied with their success if they compare it to where they were prior to their intervention efforts than if they compare it to their expectations. Greater satisfaction with progress will result in greater success in long-term behavior change. Because unmet expectations are thought to pose a greater problem for weight control, this manipulation is expected to have a greater effect on weight loss than on smoking cessation.